Geography and climate

Japan is a country of over three thousand islands extending along the Pacific coast of Asia. The main islands, running from north to south, are Hokkaidō, Honshū (the main island), Shikoku and Kyūshū. The Ryukyu Islands, including Okinawa, are a chain of islands south of Kyushū. Together they are often known as the Japanese Archipelago.

About 70% to 80% of the country is forested, mountainous,[36][37] and unsuitable for agricultural, industrial, or residential use. This is because of the generally steep elevations, climate and risk of landslides caused by earthquakes, soft ground and heavy rain. This has resulted in an extremely high population density in the habitable zones that are mainly located in coastal areas. Japan is the thirtieth most densely populated country in the world.[38]

Its location on the Pacific Ring of Fire, at the juncture of three tectonic plates, gives Japan frequent low-intensity tremors and occasional volcanic activity. Destructive earthquakes, often resulting in tsunamis, occur several times each century.[39] The most recent major quakes are the 2004 Chūetsu earthquake and the Great Hanshin Earthquake of 1995. Hot springs are numerous and have been developed as resorts.[40]

The climate of Japan is predominantly temperate, but varies greatly from north to south.[41] Japan's geographical features divide it into six principal climatic zones:

Hokkaidō: The northernmost zone has a temperate climate with long, cold winters and cool summers. Precipitation is not heavy, but the islands usually develop deep snow banks in the winter.
Sea of Japan: On Honshū's west coast, the northwest wind in the wintertime brings heavy snowfall. In the summer, the region is cooler than the Pacific area, though it sometimes experiences extremely hot temperatures, because of the Föhn wind phenomenon.
Central Highland: A typical inland climate, with large temperature differences between summer and winter, and between day and night. Precipitation is light.
Seto Inland Sea: The mountains of the Chūgoku and Shikoku regions shelter the region from the seasonal winds, bringing mild weather throughout the year.
Pacific Ocean: The east coast experiences cold winters with little snowfall and hot, humid summers because of the southeast seasonal wind.
South-west Islands: The Ryukyu Islands have a subtropical climate, with warm winters and hot summers. Precipitation is very heavy, especially during the rainy season. Typhoons are common.
The hottest temperature ever measured in Japan - 40.9 degrees Celsius - was recorded on August 16, 2007.[42]

The main rainy season begins in early May in Okinawa, and the stationary rain front responsible for this gradually works its way north until it dissipates in northern Japan before reaching Hokkaidō in late July. In most of Honshū, the rainy season begins before the middle of June and lasts about six weeks. In late summer and early autumn, typhoons often bring heavy rain.[41]

Japan is home to nine forest ecoregions which reflect the climate and geography of the islands. They range from subtropical moist broadleaf forests in the Ryūkyū and Bonin islands, to temperate broadleaf and mixed forests in the mild climate regions of the main islands, to temperate coniferous forests in the cold, winter portions of the northern islands.[43]